Ionospheric Disturbances due to the Influence of Localized Thermospheric Sources

Abstract The paper presents the results of numerical modeling of the ionospheric disturbances from spatially localized, midlatitude, thermospheric sources that simulate the dissipation effect of acoustic–gravity waves generated by phenomena on the Earth’s surface and in the lower atmosphere. The results of numerical calculations have shown that the range of ionospheric effects significantly exceeds the size of the region of sources of thermospheric disturbances and reaches low latitudes. In the spatial distribution of the critical frequency of the ionospheric F2 layer, it decreases directly above the thermospheric source and increases to the south of it. Negative ionospheric disturbances are due to a decrease in the partial concentration of atomic oxygen in the area of a thermospheric source. The processes of turbulent diffusion, which lead to a decrease in the concentration of atomic oxygen in the lower thermosphere, are most effective in reducing the electron concentration in the ionosphere. The developing large-scale circulation processes in the thermosphere lead to positive ionospheric disturbances, which are observed south of the source region up to low latitudes.